Spinal implants are often used in the surgical treatment of spinal disorders such as degenerative disc disease, disc herniations, curvature abnormalities, and trauma. Many different types of treatments are used. In some cases, spinal fusion is indicated to inhibit relative motion between vertebral bodies. In other cases, dynamic implants are used to preserve motion between vertebral bodies. In yet other cases, relatively static implants that exhibit some degree of flexibility may be inserted between vertebral bodies.
Implants such as these may be positioned between vertebral bodies, with superior and inferior surfaces placed in contact with the vertebral bodies. Often, the bone-contact surfaces of these implants are configured with a surface texture, surface features, and natural or synthetic bone growth stimulators to promote osseointegration of the implant. Recent innovations in implant materials have produced a new generation of implants constructed from polymers such as UHMWPE or PEEK. These polymer materials may offer a variety of advantages, including improved strength, reduced weight, and desirable mechanical characteristics. Unfortunately, the polymers are not naturally osteoconductive. Thus, implant constructed from these polymers may not sufficiently fuse with the vertebral bodies. Ineffective fusion at the bone-contact surface may lead to subsidence of the vertebral implants over time, and often leads to spinal instability, angular deformities, and planar translations.